path: root/kernel/sys.c

/*
 *  linux/kernel/sys.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/module.h>
#include <linux/mm.h>
#include <linux/utsname.h>
#include <linux/mman.h>
#include <linux/smp_lock.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/prctl.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/perf_event.h>
#include <linux/resource.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/workqueue.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/key.h>
#include <linux/times.h>
#include <linux/posix-timers.h>
#include <linux/security.h>
#include <linux/dcookies.h>
#include <linux/suspend.h>
#include <linux/tty.h>
#include <linux/signal.h>
#include <linux/cn_proc.h>
#include <linux/getcpu.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/seccomp.h>
#include <linux/cpu.h>
#include <linux/ptrace.h>
#include <linux/fs_struct.h>

#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/kprobes.h>
#include <linux/user_namespace.h>

#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/unistd.h>

#ifndef SET_UNALIGN_CTL
# define SET_UNALIGN_CTL(a,b)	(-EINVAL)
#endif
#ifndef GET_UNALIGN_CTL
# define GET_UNALIGN_CTL(a,b)	(-EINVAL)
#endif
#ifndef SET_FPEMU_CTL
# define SET_FPEMU_CTL(a,b)	(-EINVAL)
#endif
#ifndef GET_FPEMU_CTL
# define GET_FPEMU_CTL(a,b)	(-EINVAL)
#endif
#ifndef SET_FPEXC_CTL
# define SET_FPEXC_CTL(a,b)	(-EINVAL)
#endif
#ifndef GET_FPEXC_CTL
# define GET_FPEXC_CTL(a,b)	(-EINVAL)
#endif
#ifndef GET_ENDIAN
# define GET_ENDIAN(a,b)	(-EINVAL)
#endif
#ifndef SET_ENDIAN
# define SET_ENDIAN(a,b)	(-EINVAL)
#endif
#ifndef GET_TSC_CTL
# define GET_TSC_CTL(a)		(-EINVAL)
#endif
#ifndef SET_TSC_CTL
# define SET_TSC_CTL(a)		(-EINVAL)
#endif

/*
 * this is where the system-wide overflow UID and GID are defined, for
 * architectures that now have 32-bit UID/GID but didn't in the past
 */

int overflowuid = DEFAULT_OVERFLOWUID;
int overflowgid = DEFAULT_OVERFLOWGID;

#ifdef CONFIG_UID16
EXPORT_SYMBOL(overflowuid);
EXPORT_SYMBOL(overflowgid);
#endif

/*
 * the same as above, but for filesystems which can only store a 16-bit
 * UID and GID. as such, this is needed on all architectures
 */

int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;

EXPORT_SYMBOL(fs_overflowuid);
EXPORT_SYMBOL(fs_overflowgid);

/*
 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
 */

int C_A_D = 1;
struct pid *cad_pid;
EXPORT_SYMBOL(cad_pid);

/*
 * If set, this is used for preparing the system to power off.
 */

void (*pm_power_off_prepare)(void);

/*
 * set the priority of a task
 * - the caller must hold the RCU read lock
 */
static int set_one_prio(struct task_struct *p, int niceval, int error)
{
	const struct cred *cred = current_cred(), *pcred = __task_cred(p);
	int no_nice;

	if (pcred->uid  != cred->euid &&
	    pcred->euid != cred->euid && !capable(CAP_SYS_NICE)) {
		error = -EPERM;
		goto out;
	}
	if (niceval < task_nice(p) && !can_nice(p, niceval)) {
		error = -EACCES;
		goto out;
	}
	no_nice = security_task_setnice(p, niceval);
	if (no_nice) {
		error = no_nice;
		goto out;
	}
	if (error == -ESRCH)
		error = 0;
	set_user_nice(p, niceval);
out:
	return error;
}

SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
{
	struct task_struct *g, *p;
	struct user_struct *user;
	const struct cred *cred = current_cred();
	int error = -EINVAL;
	struct pid *pgrp;

	if (which > PRIO_USER || which < PRIO_PROCESS)
		goto out;

	/* normalize: avoid signed division (rounding problems) */
	error = -ESRCH;
	if (niceval < -20)
		niceval = -20;
	if (niceval > 19)
		niceval = 19;

	read_lock(&tasklist_lock);
	switch (which) {
		case PRIO_PROCESS:
			if (who)
				p = find_task_by_vpid(who);
			else
				p = current;
			if (p)
				error = set_one_prio(p, niceval, error);
			break;
		case PRIO_PGRP:
			if (who)
				pgrp = find_vpid(who);
			else
				pgrp = task_pgrp(current);
			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
				error = set_one_prio(p, niceval, error);
			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
			break;
		case PRIO_USER:
			user = (struct user_struct *) cred->user;
			if (!who)
				who = cred->uid;
			else if ((who != cred->uid) &&
				 !(user = find_user(who)))
				goto out_unlock;	/* No processes for this user */

			do_each_thread(g, p)
				if (__task_cred(p)->uid == who)
					error = set_one_prio(p, niceval, error);
			while_each_thread(g, p);
			if (who != cred->uid)
				free_uid(user);		/* For find_user() */
			break;
	}
out_unlock:
	read_unlock(&tasklist_lock);
out:
	return error;
}

/*
 * Ugh. To avoid negative return values, "getpriority()" will